A computer virus attack on Iran's nuclear plant could only have been designed "with nation-state support," expert say.

The Stuxnet spy worm attack did not affect the plant's system, but did hit computers of staff at the plant [AFP]

A computer virus that has attacked Iran's nuclear power plant in Bushehr could only have been designed "with nation-state support," Western cyber security experts said.

Saturday’s virus attack with a spay worm called "Stuxnet" prompted speculation that the nuclear plant may have been targeted by an enemy country in an attempt to sabotage it.

A senior official at the US technology company Symantec said that 60 percent of the computers worldwide infected by the Stuxnet worm were in Iran.

The attack did not affect the plant's system, but it did hit computers of staff at the plant and Internet providers, Iranian officials said on Sunday.

No damage

Reza Taqipour, Iran's Telecommunications Minister, said the worm had not been able to "penetrate or cause serious damage to government systems," the state-run newspaper Iran Daily reported.

"A team is inspecting several computers to remove the malware ... major systems of the plant have not been damaged," Mahmoud Jafari told the official IRNA news agency.

Authorities said Iran had identified some 30,000 Internet providers infected by the Stuxnet worm, blaming Iran's "foreign enemies for creating the virus."

Diplomats and security sources say Western governments and Israel view sabotage as one way to stymie Iran's nuclear work, which the West fears is aimed at building a nuclear weapon.

Tehran says it needs nuclear technology to generate electricity.

The malware attacks software programs that run Supervisory Control and Data Acquisition, or SCADA, systems. Such systems are used to monitor automated plants - from food and chemical facilities to power generators.

"The Stuxnet spy worm has been created in line with the West's electronic warfare against Iran," the Iran Daily quoted Mahmoud Liayi, secretary of the Information Technology Council of the Industries Ministry.

Israel, which is assumed to have the Middle East's only atomic arsenal, has hinted it could attack Iran's nuclear facilities if international diplomacy fails to curb the country's programme.